Gene therapy trial improves sight in blind toddlers

Four toddlers born with a severe form of childhood blindness have experienced “life-changing improvements” to their sight after participating in an experimental gene therapy trial. 

Before the therapy, these children, who were legally blind after experiencing a rapidly deteriorating vision from birth, could only distinguish between light and dark.

Following the treatment at Moorfields Eye Hospital, parents reported significant improvements, with some children now able to begin drawing and writing. 

Jace, one of the toddlers, received therapy at two years old. Before treatment, Jace couldn’t track objects. Now, he can pick up small toys and react to bright sunlight, marking a remarkable transformation in his ability to engage with the world. 

“This treatment has the potential to transform lives,” said professor James Bainbridge, a retinal surgeon at Moorfields Eye Hospital. “Early intervention in genetic eye diseases can make a profound difference in development and interaction with the world.” 

What does this mean for macular disease?  

This breakthrough builds on previous success in gene therapy for inherited eye diseases. Gene therapy involves adding, removing, or editing genes in cells to correct mutations that cause diseases.

The approach typically involves injecting healthy copies of a defective gene into the retina at an early stage to halt or slow degeneration. For individuals with macular disease, a similar method could be used to slow or prevent vision loss. 

The results from this trial offer hope for people with genetic forms of macular disease, potentially paving the way for treatments that restore or preserve vision.

Many macular dystrophies, such as Stargardt disease, Best disease, and Sorsby Fundus dystrophy, are caused by a mutation in a single gene.

These diseases often run in families, with children inheriting the faulty gene, leading to abnormal or dying retinal cells and resulting vision loss.

Through gene therapy, researchers hope to correct, replace, or edit the faulty genes to restore retinal cell function and prevent further degeneration. 

While conditions like Stargardt disease and other retinal dystrophies have different genetic causes, researchers are exploring ways to correct these defects through gene editing, or by silencing faulty genes.

Gene therapy and AMD 

Studies are also looking into gene therapy for age-related macular degeneration (AMD), though these work slightly differently.

In AMD, the therapy involves introducing a new gene that enables the body to produce a drug that can combat the disease, such as a treatment for wet AMD that traditionally requires frequent injections.

Gene therapy could reduce the need for repeated treatments by allowing the eye to produce its own therapeutic drug. 

Professor Andrew Lotery from the University of Southampton, describes gene therapy as an exciting area of research, showing promising results. Speaking on a recent My Macular and Me webinar, he said: “Expertise with gene therapy is increasing in ophthalmology, and I think we will see treatments for AMD, particularly for wet AMD, in the next few years.” 

Clinical trials for gene therapy 

Clinical trials are testing new treatments for inherited eye diseases, such as Stargardt disease. The Macular Society has previously funded, and continues to fund, research projects to advance gene therapy.

One example is a £120,000 co-funded study with Retina UK, led by Professor Jacqueline van der Spuy at UCL’s Institute of Ophthalmology.

This project aims to test whether a novel gene editing technique, known as prime editing, can repair a mutation that causes Stargardt disease. Currently, there are no treatments for this condition, but researchers hope this approach could offer a breakthrough in correcting the underlying genetic mutation. 

The success of this recent study at Moorfields shows that gene therapy could be a promising treatment for macular disease.

Scientists are working hard to improve gene therapy as a potential solution for stopping or slowing vision loss.

This treatment could ultimately change the lives of people affected by genetic forms of macular diseases, bringing hope to those who have previously faced limited options for their conditions.